U.S. Pat. No. 2,748,505 describes a loading apparatus with a raisable and lowerable cutting wheel provided with cutting and receiving elements for the excavated material which is positioned at an end, i.e. the front end, of a crawler bogie so as to be advanced ahead of the crawler bogie which is displaced along the ground.
Between the cutting and receiving elements of the cutter wheel, on the one hand, and the crawler bogie on the other hand, a blade extends which can transport material which has been dropped off, once again in the direction of the receiving elements of the wheel in cooperation with the obliquely disposed cutter elements thereof.
The blade can be articulated to the bogie by means of lever arms and can also be connected to the boom of the cutter wheel for raising and lowering therewith. When the cutter wheel is lifted, therefore, the blade is automatically raised and essentially maintains its position in relation to the cutting and receiving elements so that any material falling from the cutting wheel can drop to the ground to the extent that it is not fed to the receiving elements.
As a consequence humps of material can form on the ground which can impede the travel of the crawler bogie and can alter the terrain so that the excavator does not track on a level or maintain level tracking.
Since the level on which the crawler bogie may travel is thus varied, the original tracking level cannot be restored in this earlier system without a lowering of the cutter wheel, which may be undesirable, or clearing the area with other equipment such as a bulldozer or the like.
The conventional blade as described above cannot fulfill this function since it is tied to the cutter wheel boom and cannot be lowered independently.
As a consequence, the blade of U.S. Pat. No. 2,748,505 serves only for the guidance of excavated material to the receiving elements and for assisting the transfer of the excavated material to a downstream hopper which may be provided in the region of the bogie. This transfer is normally overhead.
U.S. Pat. No. 1,072,731 describes receiving elements for the excavated material which is equipped with buckets. In this system, a scraper blade is provided beneath the bogie. The scraper blade is positioned so far from the receiving element that once again material dropped from the receiving element can result in an accumulation or hump at the normal tracking level of the bogie so that here as well deviation from a level tracking cannot be avoided as the front part of the bogie rides up on these accumulations.